specify 3.7 version

Signed-off-by: Zachary Branson <[email protected]>

Author: bing-speech-trial

.travis.yml

@@ -11,7 +11,7 @@ jobs:
       env: PYTHON_VERSION=3.8
     - name: "Pandas 1.0.x"
       python: "3.7"
-      env: PYTHON_VERSION=3.7
+      env: PYTHON_VERSION=3.7.17
       env: PANDAS_VERSION=1.0.*
     - name: "Pandas 1.1.x"
       python: "3.7"